Lagadha is one of the earliest known Hindu mathematician and astronomer. This great Indian Maharishi, also known as Lagadh Muni, is believed to have lived during 1200 BC. His contribution to astronomy is still relevant.

Lagadha is ranked as the topmost astronomer because he was the redactor of Vedanga Jyotisha, which is referred to even today.

Vedanga Jyotisha has two parts: Rik and Yajur recensions. The former part contains 36 verses in Sanskrit. They deal with eclipses, a lunar calendar and units in time calculation.

Vedanga Jyotisha deals with the calculations of solar and lunar eclipses. According to Vedanga Jyotisha, the lunar month begins on a new moon day; one lunar month is 29.5 lunar days approximately; one lunar year is 12 lunar months, called lunation, and is of about 354 lunar days.

A lunar month is divided into 30 equal parts called tithi. A period of 19 lunar years is called a Lagadha era.

Lagadha Yuga begins on a new moon day which coincides with winter solstice, i.e., December 22.

He developed oral methods for calculations of ellipse, and also for elementary arithmetic.

He was the first to suggest the concept of yuga (era), a period of cycle of repeating astronomical events.

Information about his personal life and other such details are yet to be discovered.

Source -Development of Astronomical Observation in Vedic and Post-Vedic India (1993) - Indian Journal of History of Science (185 - 251) by Yukio OhashiIndian Astronomy - An Introduction (2000) published by Hyderabad University Press by Balachandra S Rao.